" said Jack, "because you know the route. And
be quick."

Swiftly, yet withal cautiously, because the cave might be defended,
they approached the big rock. As they sidled around it, a gleam of
light from the mouth of the cave at the rear of the rock fell athwart
their path. Involuntarily they drew back.

Then Jack brushed Tom Bodine aside and took the lead. His repeater
thrust before him, crouching, he entered the mouth of the cave. A
moment later his whisper came back:

"Coast's clear."

But the others already were at his heels.

A hasty glance around revealed the first of the two chambers, which
Tom had said the cave possessed, was luxuriously furnished and lighted
by a powerful electric bulb enclosed in a huge frosted globe suspended
from the middle of the roof. There was no time for further
investigation because Jack already was pushing on toward the heavy
hangings at the rear covering the mouth of the second chamber, and the
others clung to his heels.

Parting the hangings quickly, Jack threw his rifle to his shoulder.
Then he and his companions received their second big surprise. The
room was empty of human occupants. But it, too, was brilliantly
lighted.

And it was a radio broadcasting station.

To the trained eyes of the boys that much was apparent at first
glance. In one corner of the tremendous cave hummed the dynamo. From
it, of course, came also the electricity for the lights. Before they
could pursue their investigations, however, Tom Bodine, who had
dropped back to the outer entrance, issued a warning hiss. Then he
darted across the outer room and joined them.

"Three of 'em," he whispered. "They'll be here in a minute."

"Good," said Jack, taking command. "We'll give them a surprise. These
hangings are fastened to rings on a big pole up above us there, and
they'll slide easily. Tom, you and Bob grab the hangings in the middle
and be ready to pull them aside when I say the word. Frank, you and I
will stand here in the middle and keep them covered."

All took their assigned positions as the sound of voices was heard at
the outer entrance. Jack peered between the two folds of the hangings
and smiled with satisfaction.

"Let's go," he said.

The hangings flew aside.

CHAPTER XVIII

THE FIGHT IN THE CAVE

"Hands up, gentlemen," ordered Jack, rifle to shoulder.

"And be quick about it," added Frank, revolver extended.

Tom and Bob, the hangings disposed of, ranged themselves on